Achieving Target Antifactor Xa Activity with a Heparin Protocol Based on Sex, Age, Height, and Weight

Rosborough, Terry K.; Shepherd, Michele F.

doi:10.1592/phco.24.8.713.36067

Cited by 30 publications

(27 citation statements)

References 59 publications

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“…Time to achieve threshold aPTT in the control group of our study was comparable to findings of previous studies evaluating standard care weight-base nomogram in nonobese patients (23)(24)(25)(26)(27). Few studies have addressed the issues of UFH dosing in the obese (21,25,(27)(28)(29).…”

Section: Obesitysupporting

confidence: 86%

“…Interestingly, they did not find a difference in the time to first therapeutic aPTT between obese and nonobese patient. This may be explained by a time to therapeutic aPTT for nonobese patients of 30.0 6 77.0 hours, which is at odd with our results and previous studies (23)(24)(25)(26)(27) involving nonobese patients. This could be since, unlike the present study, most patients in the study from Riney et al (20) did not receive an initial bolus.…”

Section: Obesitycontrasting

confidence: 48%

“…Few studies have addressed the issues of UFH dosing in the obese (21,25,(27)(28)(29). Moreover, controversy exists whether total body weight or ideal body weight provides better anticoagulation results (29).…”

Section: Obesitymentioning

confidence: 99%

“…Moreover, controversy exists whether total body weight or ideal body weight provides better anticoagulation results (29). Available literature seems to support the use of total body weight with specified maximum initial bolus and infusion rates for obese patients (21,25,27,28). Maximum doses were suggested to avoid higher aPTTs than desired and an increased risk of bleeding as heparin requirements do not increase linearly with obese body weight (20,21).…”

Section: Obesitymentioning

confidence: 99%

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Delayed efficient anticoagulation with heparin in patients with a weight of 110 kg and more treated for acute coronary syndrome

Joncas

Poirier

Ardilouze

et al. 2013

Obesity

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Objective: The use of a weight-based nomogram is considered as standard care for prescribing appropriate doses of unfractionated heparin (UFH). Because of the need for multiple other medications that may affect bleeding and that clinical data have relied on similar dosing algorithms, maximum initial bolus and infusion rates have been suggested (capped initial dose). Whether these weight-based heparin nomograms properly address therapeutic dosing in obese patients remains questionable. Design and Methods: Thirty patients treated for acute coronary syndrome and weighing !110 kg were retrospectively compared with 90 controls (three groups of 30 patients, weighting 50-69.9, 70-89.9, or 90-109.9 kg), all treated with UFH, July 2008 to April 2009. The primary end point was the time required to obtain a threshold activated partial thromboplastin time (aPTT). Results: Mean time to achieve threshold aPTT was longer for obese patients weighing !110 kg than for controls (31.47 vs. 12.89 hours; P < 0.0001). At 24 hours, 63% of obese patients weighing !110 kg had not reached threshold aPTT vs. 7% of controls (P < 0.0001). However, threshold infusion rate did not differ between weight categories (13.0 vs. 13.1 U/kg/h; P ¼ NS) and approximated the initial infusion rate recommended by nomograms without applying the dose cap (12 U/kg/h). Conclusions: Adequate anticoagulation time doubled in patients weighing !110 kg, suggesting that these patients were not receiving appropriate heparin doses initially to achieve threshold aPTT rapidly. Using initial infusion rate recommended by a nomogram without capping for total body weight is suggested as acceptable in this study. This approach should be further evaluated in a prospective study.

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Section: Obesitysupporting

confidence: 86%

Section: Obesitycontrasting

confidence: 48%

Section: Obesitymentioning

confidence: 99%

Section: Obesitymentioning

confidence: 99%

See 2 more Smart Citations

Delayed efficient anticoagulation with heparin in patients with a weight of 110 kg and more treated for acute coronary syndrome

Joncas

Poirier

Ardilouze

et al. 2013

Obesity

View full text Add to dashboard Cite

show abstract

“…A literature search conducted in early 2008 yielded only one published protocol that utilized antifactor Xa levels for heparin monitoring. 15 That protocol used estimated blood volume as the basis for determining the bolus doses and initial infusion rate and employed a computerized nomogram for management. In contrast, our institution sought a weight-based protocol similar to the one then in use, which was based on that published by Raschke et al 2 Therefore, we devised a weight-based protocol utilizing antifactor Xa levels to monitor heparin.…”

mentioning

confidence: 99%

Weight-based heparin protocol using antifactor Xa monitoring

Smith

Wheeler

2010

American Journal of Health-System Pharmacy

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Antifactor Xa Levels versus Activated Partial Thromboplastin Time for Monitoring Unfractionated Heparin

2012

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Intravenous unfractionated heparin (UFH) remains an important therapeutic agent, particularly in the inpatient setting, for anticoagulation. Historically, the activated partial thromboplastin time (aPTT) has been the primary laboratory test used to monitor and adjust UFH. The aPTT test has evolved since the 1950s, and the historical goal range of 1.5-2.5 times the control aPTT, which first gained favor in the 1970s, has fallen out of favor due to a high degree of variability in aPTT readings from one laboratory to another, and even from one reagent to another. As a result, it is now recommended that the aPTT goal range be based on a corresponding heparin concentration of 0.2-0.4 unit/ml by protamine titration or 0.3-0.7 unit/ml by antifactor Xa assay. Given that several biologic factors can influence the aPTT independent of the effects of UFH, many institutions have transitioned to monitoring heparin with antifactor Xa levels, rather than the aPTT. Clinical data from the last 10-20 years have begun to show that a conversion from aPTT to antifactor Xa monitoring may offer a smoother dose-response curve, such that levels remain more stable, requiring fewer blood samples and dosage adjustments. Given the minimal increased acquisition cost of the antifactor Xa reagents, it can be argued that the antifactor Xa is a cost-effective method for monitoring UFH. In this review, we discuss the relative advantages and disadvantages of the aPTT, antifactor Xa, and protamine titration tests, and provide a clinical framework to guide practitioners who are seeking to optimize UFH monitoring within their own institutions.

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Achieving Target Antifactor Xa Activity with a Heparin Protocol Based on Sex, Age, Height, and Weight

Abstract: A UFH dosage protocol based on patient sex, age, height, and weight produced improved initial target antifactor Xa levels compared with a weight-based protocol. The protocol is computerized and easy to apply.

Cited by 30 publications

References 59 publications

Delayed efficient anticoagulation with heparin in patients with a weight of 110 kg and more treated for acute coronary syndrome

Delayed efficient anticoagulation with heparin in patients with a weight of 110 kg and more treated for acute coronary syndrome

Weight-based heparin protocol using antifactor Xa monitoring

Antifactor Xa Levels versus Activated Partial Thromboplastin Time for Monitoring Unfractionated Heparin

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